“Equine laminitis” is known to be an inflammation of the lamellar connection between the sensitive, vascular portion, that extends along the third phalanx of the foot, and the insensitive hoof wall, resulting in their partial separation. This prevents the horse's weight from being borne by the hoof wall, transferring the load to the sole which becomes flat or convex, and to the coronary band, causing it to sink.
Laminitis generally affects the forefeet, but it is not infrequent for the hind feet to be also affected.
Its causes are not fully understood; nevertheless, because inflammation is caused by an abnormal release of histamines, the possible causes can be chiefly identified as: incorrect diet, excessive drug administration, work on very hard surfaces, untreated infections, etc.
The most evident symptoms are: shifting of weight from the front to the hind feet, lameness, heat in the hoof, incorrect gait with feet placed very far forward or very far back.
If left untreated, this pathology leads to the destruction of the dermal laminae, with consequent separation of the insensitive laminae from the sensitive laminae, starting from the anterior part of the hoof and spreading medially and laterally downward.
This process, which causes separation of the foot from the load bearing structure (hoof), produces sinking of the third phalanx (finger bone) with downward rotation of its tip, to the point of penetrating through the sole. It is clear that, if not adequately treated, laminitis can lead to loss of foot function that, in severe cases, may require euthanizing the animal.
There is thus a strong need for treatment methods capable of curing this condition.
Currently, there exist various “mechanical” types of interventions such as:
inverting the shoeing, putting the foot in a cast, application of a boot, refrigerated leg pieces, cold foot baths.
All these solutions have significant drawbacks, chiefly connected with the fact that they do not produce a full and speedy recovery, and also often require a person to continuously attend to the animal. Another known solution consists of using a rubber boot fitted over the hoof. These boots, made of natural or synthetic rubber, can be of two types. One type is a simple rubber boot worn over the shod hoof, that is used in “endurance” races to help absorb the impact on the hoof and prevent it from slipping on the terrain.
The second type of boot is fitted on the unshod hoof, and incorporates a sole angled 20° toward the front. Such boots are used for treating laminitis but with poor results, because they only keep the hoof statically in an inclined position, determined by the angle of the sole. This angle causes the “pulvinus coronae” valve to open, facilitating blood flow in the foot, but without any other beneficial effects.
Because a horse suffering from laminitis must be kept at rest inside a box, its foot does not receive the blood pumping action produced by normal walking and foot movements.
In this condition, even the application of refrigerated leg pieces produces poor results because, without the pumping action, blood stagnates in the foot without transferring the cooling to internal tissues. Furthermore, these leg pieces stop at the hoof wall, leaving uncovered precisely the part of the sole affected by the inflammation (laminitis).